1. Field of the Invention
The present invention relates to a lens driving device for detecting an original position of a lens and for controlling a lens position, and further relates to an electronic camera using the lens driving device.
2. Description of the Related Art
In recent years, electronic cameras are widely used. This kind of the electronic camera is downsized and lightened for the purpose of improving portability. Moreover, it is general to install the electronic camera in a small-sized equipment of a cell-phone, a PDA (Personal Digital Assistant) and so forth. In such a case, it is required to further downsize and lighten the electronic camera. Thus, it is also desired to downsize a lens driving device to be employed in the electronic camera.
In order to solve the above problems, a lens driving device utilizing a hollow stepping motor is considered (see Japanese Patent Laid-Open Publication No. 60-417, for instance). This kind of the lens driving device comprises a lens holder for holding a lens, a hollow rotor disposed so as to cover the periphery of the lens holder, and a stator disposed so as to cover the periphery of the hollow rotor. By supplying a pulse current to the stator, the hollow rotor is rotated to move the lens holder in an optical-axis direction via a cam mechanism or the like. By unifying the stepping motor and a lens barrel, it is possible to downsize the lens driving mechanism.
Meanwhile, in the lens driving device, it is important to detect an original position of the lens for the purpose of accurately controlling a lens position. The original position of the lens is detected by an optical position detector of a photo interrupter (hereinafter, called as PI) and so forth. However, the lens driving device described in the above-noted Publication No. 60-417 has no space for disposing the optical detector of the PI and so forth. Consequently, if the original position is detected by using the optical position detector of the PI and so forth, there arises a problem in that the lens driving device becomes a large-size.